JP3750643B2 - Image reading device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image reading apparatus which can be applied to an image forming apparatus such as a copying machine or a facsimile machine and which can read both sides of a document.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an image forming apparatus equipped with an automatic document feeder (ADF), a sheet fixing type in which an original is conveyed by a conveying belt and positioned on a platen glass, and a scanner moves under the platen glass to read the original. A sheet-through type is known in which a scanner is stopped below a platen glass and the original is read while being conveyed on the platen glass at a constant speed.
[0003]
When scanning both sides of a document, the sheet-fixed type temporarily stops the document on the platen glass. Therefore, in order to scan both sides, it is necessary to reverse the document and then stop the document again. There is a drawback. In the sheet-through type, for example, as described in Patent Document 1, two reading units are used to be arranged on both sides of a conveyance path through which a document is conveyed, and the front and back surfaces of the document are conveyed once. It is done to read in. By doing this, the number of reading means increases, but the document can be transported only once, and the reading processing time can be shortened.
[0004]
Although the conventional image reading apparatus using two such reading means has advantages such as shortening the reading processing time, there is a portion set in a narrow interval between the reading means and the platen in the document transport path. Naturally, the occurrence of jamming at the time of document conveyance increases, and dirt such as paper dust generated when the document is conveyed adheres to the two reading means. Need to be done.
[0005]
In order to cope with such a problem, for example, in Patent Document 2, a white reference surface is provided only when image correction is necessary by rotating a white guide roller disposed opposite to a reading surface of an image sensor that reads an original. The document describes that the white reference surface is prevented from being stained by facing the reading surface and facing the guide surface when the document is otherwise conveyed.
[0006]
Considering the frequency of the single-sided reading operation and the double-sided reading operation, since the single-sided reading operation is overwhelmingly large, the second reading unit is used in the first reading unit used for single-sided reading and the second reading unit used for double-sided reading. Although the frequency is low, it is inevitable that dirt such as paper dust always adheres and the reading surface deteriorates.
[0007]
[Patent Document 1]
JP-A-1-194658 [Patent Document 2]
JP 2001-313794 A
[Problems to be solved by the invention]
However, considering the frequency of the single-sided reading operation and the double-sided reading operation, the single-sided reading operation is overwhelmingly large, so that the first reading unit used for single-sided reading and the second reading used for double-sided reading as in the conventional technique described above. In the case where the second reading means is used, it is inevitable that dirt such as paper dust always adheres and the reading surface deteriorates even though the second reading means is used less frequently.
[0009]
Therefore, the present invention provides an image reading apparatus capable of reading both sides of a document provided with two reading means, and the reading means used only for double-sided reading includes an image reading apparatus configured to convey a document only during double-sided reading. It is intended to provide.
[0010]
[Means for Solving the Problems]
An image reading apparatus according to the present invention includes a main conveyance unit that conveys a document in a main conveyance path, a first reading unit that is arranged in the main conveyance path and reads one surface of the document, and a first reading unit A sub-transport path that merges with the main transport path on the upstream side and is provided on the inner surface of the upper cover and is set by opening the upper cover; A sub-conveying means for conveying the image, a second reading means arranged on the sub-conveying path for reading the other side of the document, and conveying the document to the main conveying path by the main conveying means. Only one-side reading control means for reading by the first reading means, and the original is conveyed to the sub-conveying path and the main conveying path by the sub-conveying means and the main conveying means, and both sides of the original are the first and first 2 readers Characterized in that it comprises a double-sided reading control means for reading the. Further, the double-sided reading control unit controls the original to be conveyed to the main conveyance path by the main conveyance unit and carried into the sub conveyance path. Furthermore, a detecting means for detecting opening and closing of the upper cover is provided, and the double-sided reading control means is operated in response to an open state detection signal from the detecting means. Further, the apparatus further comprises drive transmission means for connecting the sub-transport means to the main transport means in conjunction with the opening operation of the upper cover.
[0011]
With the configuration as described above, the second reading unit is arranged in the sub-transport path, and the original does not pass through the sub-transport path while the single-sided scanning control unit is operated. The surface never gets dirty. Further, since the sub-conveying path is joined to the main conveying path on the upstream side of the first reading means, both sides of the original can be read by one original conveyance, and the reading processing time almost the same as the conventional one can be obtained. Can be maintained.
[0012]
Further, when the double-sided reading is controlled so that the original is transported to the main transport path by the main transport unit and then transported to the sub-transport path, it is transported by the main transport unit from the same document tray as in the single-sided scanning operation. be able to.
[0013]
In addition, by providing a double-sided document tray in the sub-transport path, it is possible to stably hold a document once transported to the sub-transport path, and to reliably perform a transport operation when reading a double-sided document. It becomes. If the double-sided document tray is formed on the inner surface of the upper cover, the upper cover is closed and the double-sided document tray is accommodated except when the double-sided reading operation is performed, and the size can be reduced. Furthermore, if the detection unit detects that the upper cover is opened and operates the double-sided reading unit, the operation for performing double-sided reading can be simplified. Further, if the sub-transport means is connected to the main transport means in conjunction with the opening operation of the upper cover, it is not necessary to separately provide a drive source for the sub-transport means, and the mechanism of the transport means can be made compact.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments according to the present invention will be described in detail. FIG. 1 is a schematic sectional view of an entire image forming apparatus to which an image reading apparatus according to the present invention can be applied. A document transport unit 1 and a document reading unit 2 for reading a document are arranged at the upper part of the image forming apparatus, and a recording unit 3 for recording an image, a sheet transport unit 4 for transporting a sheet for recording an image, and two feeding units are disposed below the document transport unit 1. Paper sections 5 and 6 are arranged.
[0015]
In the document transport unit 1, a document is carried in by a document tray 10, a pickup roller 11, a separation roller 12 and a retard roller 13. In other words, the document placed on the document tray 10 is drawn by the pickup roller 11, and the leading end of the document is sandwiched between the separation roller 12 and the retard roller 13. The separation roller 12 rotates clockwise to pull in the document, but the retard roller 13 also rotates clockwise to prevent the document from being pulled in. Therefore, the double feeding of the document is prevented and the document is It is carried in one by one. Next, the document is nipped and conveyed by the feed roller 14 and the press roller 15, and the leading end of the document reaches between the feed roller 16 and the press roller 17 along the guide. Here, when the leading edge of the document is detected by the document detection sensor, the feed roller 16 starts transporting, the leading edge of the document is sandwiched between the feed roller 18 and the press roller 19, and the document is transported at a constant speed. . Meanwhile, the document is read by the document reading unit 2 on the platen 23. The document thus conveyed and read is conveyed between the discharge roller 20 and the press roller 21 and is carried out to the document discharge tray 22.
[0016]
In the document reading unit 2, light is irradiated toward the platen 23 by the lamp 24, and reflected light from the document is guided to the CCD 25 by a mirror and converted into an electrical signal.
[0017]
In the recording unit 3, a toner container 26, a charging brush 29, a photosensitive drum 30, a transfer roller 31, an exposure head 32, and a fixing roller 33 are provided for recording on the sheet conveyed by the sheet conveying unit 4. First, the surface of the photosensitive drum 30 is uniformly charged by the charging brush 29, and an electrostatic latent image is formed by exposing the charged photosensitive drum 30 according to an image recording signal by the exposure head 32. Next, the toner in the toner container 26 is transferred from the supply roller 27 to the electrostatic latent image formed on the photosensitive drum 30 via the developing roller 28 to be visualized, and the surface of the photosensitive drum 30 is transferred by the transfer roller 31. The toner image formed on the sheet is transferred to a sheet. The transferred toner image is sandwiched between the fixing roller 33 and the press roller 34 and heated and pressed to be fixed on the paper.
[0018]
In the paper transport unit 4, the paper loaded in the paper feed cassettes 43 of the paper feed units 5 and 6 is drawn by the pickup roller 35 and is sandwiched and transported between the feed roller 36 and the press roller 37. The transported paper is transported along the paper guide, and is sandwiched between the feed roller 38 and the press roller 39 and transported to the recording unit 3. As described above, the sheet conveyed to the recording unit 3 is conveyed between the transfer roller 31 and the photosensitive drum 32 to transfer the toner image, and is sandwiched between the fixing roller 33 and the press roller 34 so that the toner image is transferred. After being fixed, the paper is sandwiched between the discharge roller 40 and the press roller 41 and is carried out to the paper discharge tray 42.
[0019]
FIG. 2 is an example of the document conveying unit 1 when the present invention is applied to the above-described image forming apparatus. A switching guide 54 is provided in the vicinity of the feed roller 16 disposed on the upstream side of the document reading unit 2 in the document transport path. As will be described later, the switching guide 54 guides a document conveyed by rotating in the vertical direction when performing single-sided reading control and double-sided reading control of the document. Adjacent to the switching guide 54, a CIS 50 and a white roller 51 are arranged opposite thereto. A feed roller 52 and a press roller 53 are arranged in parallel with the CIS 50 and the white roller 51. In this example, a white roller facing the CIS 50 is used, but a white plate may be used. Further, instead of the switching guide 54, one conveyance path may be closed with a flexible elastic piece, such as a film. By making this film part of the main transport path, it can also serve as a guide for the document transported on the main transport path.
[0020]
An apparatus cover is provided so as to cover the upper part of the document conveying section 1, and a part of the apparatus cover is an upper cover 56 having a double-sided document tray formed on the inner surface. Thus, both are attached at almost equal intervals. The upper cover 56 is attached to a hinge 59 having a rotation axis coaxial with the feed roller 52 and is rotatable. The document detection sensor 60 is installed between the feed roller 16 and the platen 23, and the other document detection sensor 61 is installed between the white roller 51 and the feed roller 52.
[0021]
When performing the single-sided reading operation of the document, the upper cover 56 is accommodated in the apparatus cover and closed as shown in FIG. Therefore, the guides 57 and 58 constituting the double-sided document tray are accommodated in the apparatus. In the single-sided reading operation mode, the switching guide 54 rotates downward and is set at the position shown in the figure. The document placed on the document tray 10 is first drawn in the direction indicated by the arrow (A) by the separation roller 12 and the retard roller 13, and is nipped between the feed roller 14 and the press roller 15 and conveyed. As described above, the document is sandwiched between the feed roller 16 and the press roller 17 and conveyed in the direction indicated by the arrow (B), and the lower surface of the document is read by the CCD 25. Then, it is conveyed between the discharge roller 20 and the press roller 21 and is carried out to the document discharge tray 22 as indicated by an arrow (C). As described above, since no original passes through the CIS 50 during the single-sided reading operation, dirt such as paper dust does not adhere to the CIS 50.
[0022]
When performing the double-sided reading operation of the document, as shown in FIG. 3, when the upper cover 56 is opened, the guides 57 and 58 are set so as to correspond to the nip portions of the feed roller 52 and the press roller 53. The The opening of the upper cover 56 may be detected by a detection means such as an optical detection sensor and automatically switched to the double-sided reading operation mode. Then, when switching to the double-sided reading operation mode, the switching guide 54 rotates downward and is set at a position indicated by a dotted line in the figure. The document placed on the document tray 10 is drawn in the direction indicated by the arrow (D) by the separation roller 12 and the retard roller 13 and sandwiched between the feed roller 14 and the press roller 15 as in the case of single-sided reading. It is conveyed, nipped between the feed roller 16 and the press roller 17 and conveyed in the direction indicated by the arrow (E). When the trailing edge of the document is detected by the document detection sensor 60, the transport operation is temporarily stopped. Next, the switching guide 54 is rotated upward and set at a position indicated by a solid line in the figure. When the feed rollers 16 and 18 are driven and the document is conveyed in the reverse direction as shown by the arrow (F), the document passes between the CIS 59 and the white roller along the switching guide 54, and the feed roller 52 and the press roller. 53, and is carried between guides 57 and 58, which are double-sided document trays, as indicated by arrows (G). When the document detection sensor 61 detects the trailing edge of the document, the conveying operation is stopped.
[0023]
Then, as shown in FIG. 4, the feed roller 52 is driven to convey the document carried in the double-sided document tray in the direction indicated by the arrow (H), and the upper surface of the document is read by the CIS 50. The read original is conveyed between the feed roller 16 and the press roller 17 along the switching guide 54, and the lower surface of the original is read by the CCD 25 while being conveyed in the direction indicated by the arrow (I). Then, it is conveyed between the discharge roller 20 and the press roller 21 and is carried out to the document discharge tray 22 as indicated by an arrow (J). In this way, both sides of the document are read simultaneously by one transport operation.
[0024]
FIG. 5 shows an example of a drive transmission mechanism to the feed roller 52. FIG. 5A is a state diagram in the single-sided scanning operation mode, and FIGS. 5B and 5C are state diagrams in the double-sided scanning operation mode. A drive gear 70 is fixed to the rotation shaft of the feed roller 16, and an idle gear 71 is engaged with the drive gear 70, and the idle gear 71 is rotatably supported on the rotation shaft. Idle gears 72 and 73 are pivotally supported on the member 75 and mesh with the idle gear 71. The support member 75 is biased so as to rotate clockwise around the rotation shaft of the idle gear 71 by a biasing means such as a spring (not shown).
[0025]
On the other hand, a drive gear 74 is fixed to the rotation shaft of the feed roller 52. In addition, a locking member 76 that rotates about the rotation axis of the feed roller 52 in conjunction with the opening / closing operation of the upper cover 56 is provided.
[0026]
As shown in FIG. 5A, in the single-sided reading operation mode, the locking member 76 rotates toward the feed roller 16 and locks the support member 75. By being locked by the locking member 76, the idle gears 72 and 73 attached to the support member 75 remain at a position separated from the drive gear 74. Accordingly, the driving force of the feed roller 16 is not transmitted to the feed roller 52. Then, as shown in FIG. 5C, when the upper cover 56 is opened in the double-sided reading operation mode, the locking member 76 rotates counterclockwise and the locked state with the support member 75 is released. Is done. Then, the support member 75 rotates clockwise by the biasing means described above so that the idle gear 73 meshes with the drive gear 74, and the driving force of the feed roller 16 is fed through the gear group described above. The document is conveyed and rotated, and the document is transported.
[0027]
As shown in FIG. 3, when the document is conveyed from arrow (F) to (G), the feed roller 16 rotates clockwise, so that the drive gear 70 rotates clockwise and the idle gear 71 rotates counterclockwise. Rotate to. Therefore, as shown in FIG. 5B, the idle gear 72 moves around the idle gear 71 and meshes with the drive gear 74. Thus, the driving force is transmitted to the driving gear 74 and the feed roller 52 rotates counterclockwise. As shown in FIG. 4, when the document is conveyed from the arrow (H) to (I), the feed roller 16 rotates counterclockwise, so that the drive gear 70 rotates counterclockwise, and the idle gear 71. Rotates clockwise. Then, as shown in FIG. 5C, the driving force is transmitted in a state where the idle gear 73 is engaged with the driving gear 74, and the feed roller 52 rotates clockwise.
[0028]
FIG. 6 shows an outline of a block configuration relating to control of the entire image forming apparatus. In the document transport unit 1 and the document reading unit 2, detection signals from the document set sensor 80, the document detection sensor 60, the document detection sensor 61, and the upper cover sensor 83 are transmitted to the CPU 84 via the ADF bus and the main body bus. The CPU 84 performs arithmetic processing using the program stored in the ROM 85 or the CODEC 89, and temporarily stores data in the SRAM 86 and the DRAM 87 as necessary. Control signals from the CPU 84 are output to the transport motor 80, the transport clutch 81, the first reading means (CCD) 25, and the second reading means (CIS) 50 via the main body bus and the ADF bus, respectively. In addition, an image signal necessary for image formation and a control signal therefor are output to the recording unit 3. In the operation unit 88, data designated by the operator is input, an alarm, a message, or the like is displayed.
[0029]
An example of performing a single-sided reading operation and a double-sided reading operation of a document with such a configuration will be described using the flow shown in FIG.
[0030]
First, opening / closing of the upper cover 56 is detected (S100). When the closed state is detected by the upper cover sensor 83, the mode is shifted to the single-sided reading mode. When the opened state is detected, the mode is shifted to the double-sided reading mode. . In the single-sided reading mode, when the document set sensor 82 detects that a document is set on the document tray 10 (S101), the transport clutch 81 is turned on and the transport motor 80 is started (S102). When the conveyance of the document is started and the document detection sensor 60 detects the leading edge of the document and is turned on (S103), the CCD 25 starts a reading operation (S104). When the document is conveyed and one side is read and the document detection sensor 60 detects the trailing edge of the document and is turned off (S105), the CCD 25 ends the reading operation (S106).
[0031]
On the other hand, in the duplex reading mode, when the document set sensor 82 detects that a document is set on the document tray 10 (S110), the transport clutch 81 is turned on and the transport motor 80 is started (S111). When the conveyance of the document is started and the document detection sensor 60 detects the document and then detects the trailing edge of the document and is turned OFF, the conveyance is temporarily stopped (S112). Then, the switching operation of the switching guide 54 is performed, the document is transported in the reverse direction, and the document is carried into the sub transport path (S113). When the document detection sensor 61 detects the document and detects the trailing edge of the document and is turned OFF, the reverse conveyance is temporarily stopped (S114). After a predetermined time has passed, the conveyance is started again (S115), and when the document detection sensor 61 detects the leading edge of the document and is turned on (S116), the reading operation of the CIS 50 is started (S117). When the document is further conveyed and the document detection sensor 60 detects the leading edge of the document and is turned on (S118), the reading operation of the CCD 25 is started (S119). When the document is further conveyed and the document detection sensor 60 detects the trailing edge of the document and is turned off (S122), the reading operation of the CCD 25 is completed (S123). When it is detected that the document is conveyed to the main conveyance path and discharged to the document discharge tray 22, the conveyance clutch 81 is turned off and the conveyance motor 80 is stopped.
[0032]
In FIG. 7, during the duplex scanning operation, the document is transported in the opposite direction and then transported in the sub-transport path and then the duplex scanning is performed. However, when the document is transported for the first time, the CCD 25 firstly scans one side of the document. , And then transported in the reverse direction to carry the original into the sub-transport path and read the other surface by the CIS 50. By controlling the double-sided reading operation in this way, the reading operation by the CCD 25 and the reading operation by the CIS 50 do not overlap, and image processing can be simplified and the memory capacity can be suppressed. An example is shown in FIG.
[0033]
In FIG. 8, the single-sided reading mode (S100 to S106) is the same as that in FIG. In the duplex reading mode, when the document set sensor 82 detects that a document is set on the document tray 10 (S210), the transport clutch 81 is turned on and the transport motor 80 is started (S211). When the conveyance of the document is started and the document detection sensor 60 detects the leading edge of the document and is turned on (S212), the reading operation of the CCD 25 is started (S213). When the document detection sensor 60 detects the trailing edge of the document and is turned off, the conveyance is temporarily stopped (S214), and the reading operation of the CCD 25 is terminated (S215). Thereafter, a switching operation of the switching guide 54 is performed, the document is conveyed in the reverse direction, and the document is carried into the sub-conveying path (S216). When the document detection sensor 61 detects the document and detects the trailing edge of the document and is turned OFF, the reverse conveyance is once stopped (S217). After a predetermined time has passed, the conveyance is started again (S218). When the document detection sensor 61 detects the leading edge of the document and is turned on (S219), the reading operation of the CIS 50 is started (S220). When the document detection sensor 61 detects the trailing edge of the document and is turned off (S221), the reading operation of the CIS 50 ends (S222). When it is detected that the document is conveyed to the main conveyance path and discharged to the document discharge tray 22, the conveyance clutch 81 is turned off and the conveyance motor 80 is stopped.
[0034]
In the embodiment described above, the document is set on the document tray 10 in both the single-sided reading operation and the double-sided scanning operation. However, the document may be directly set on the double-sided document tray during the double-sided reading operation. In this way, the time required for the double-sided reading operation can be further shortened.
[0035]
In the above embodiment, the double-sided document tray is formed on the inner surface of the upper cover 56. However, the double-sided document tray may be attached to the apparatus main body so that it can be pulled out and pulled out during the double-sided reading operation.
[0036]
【The invention's effect】
As described above, according to the present invention, the second reading unit is disposed in the sub-transport path, and the original does not pass through the sub-transport path while the single-sided scanning control unit operates. The surface never gets dirty. Further, since the sub-conveying path is joined to the main conveying path on the upstream side of the first reading means, both sides of the original can be read by one original conveyance, and the reading processing time almost the same as the conventional one can be obtained. Can be maintained.
[0037]
Further, when the double-sided reading is controlled so that the original is transported to the main transport path by the main transport unit and then transported to the sub-transport path, it is transported by the main transport unit from the same document tray as in the single-sided scanning operation. be able to.
[0038]
In addition, by providing a double-sided document tray in the sub-transport path, it is possible to stably hold a document once transported to the sub-transport path, and to reliably perform a transport operation when reading a double-sided document. It becomes. If the double-sided document tray is formed on the inner surface of the upper cover, the upper cover is closed and the double-sided document tray is accommodated except when the double-sided reading operation is performed, and the size can be reduced. Furthermore, if the detection unit detects that the upper cover is opened and operates the double-sided reading unit, the operation for performing double-sided reading can be simplified. Further, if the sub-transport means is connected to the main transport means in conjunction with the opening operation of the upper cover, it is not necessary to separately provide a drive source for the sub-transport means, and the mechanism of the transport means can be made compact.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of an entire image forming apparatus to which an embodiment according to the invention can be applied.
FIG. 2 is a schematic sectional view of an embodiment according to the present invention.
FIG. 3 is a schematic cross-sectional view when an upper cover according to an embodiment of the present invention is opened.
4 is an operation explanatory diagram of FIG. 4. FIG.
FIG. 5 is a schematic view of a drive roller drive transmission mechanism.
FIG. 6 is a block configuration diagram relating to control of an image forming apparatus to which an embodiment according to the invention is applied.
FIG. 7 is a flowchart at the time of document conveyance according to the embodiment of the present invention.
FIG. 8 is another flowchart at the time of document conveyance according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Document conveyance part 2 Document reading part 3 Recording part 4 Paper conveyance part 5 Paper feed part 6 Paper feed part
11 Pickup roller
12 Feed roller
13 retard roller
14 Feed roller
15 Press roller
16 Feed roller
17 Press roller
18 Feed roller
19 Press roller
20 Discharge roller
21 Press roller
23 Platen
24 lamp
25 CCD
50 CIS
51 White roller
52 Feed roller
53 Press roller
54 Switching guide
56 Top cover
57 Guide
58 Guide
59 Hinge
60 Document detection sensor
61 Document detection sensor
70 Drive gear
71 Idle Gear
72 Idle Gear
73 Idle Gear
74 Drive gear
75 Support member
76 Locking member

Claims (4)

A main transport unit that transports a document in the main transport path, a first reading unit that is disposed in the main transport path and reads one surface of the document, and joins the main transport path upstream of the first reading unit. And a sub-conveying path formed on the inner surface of the upper cover and provided with a double-sided document tray set by opening the upper cover, a sub-conveying means for conveying the original in the sub-conveying path, A second reading unit arranged in a sub-conveying path for reading the other side of the original; and a single side for conveying the original to the main conveying path by the main conveying unit and reading only one side of the original by the first reading unit. Reading control means and double-sided reading control for conveying the original to the sub-conveying path and the main conveying path by the sub-conveying means and the main conveying means and reading both sides of the original by the first and second reading means Image reading apparatus characterized by comprising a stage.   2. The image reading apparatus according to claim 1, wherein the double-sided reading control unit controls the original to be transported to the main transport path by the main transport unit and then transported to the sub-transport path. 3. 3. The image reading according to claim 1, further comprising a detection unit configured to detect opening and closing of the upper cover, and the double-sided reading control unit is operated in response to an open state detection signal from the detection unit. apparatus. The image reading apparatus according to any one of claims 1-3, characterized in that it comprises a drive transmission means connecting the sub-carrier means in conjunction with the opening operation of the upper cover to said main conveying means.

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